Intro-Java/Recursion.java at master · Liebmann5/Intro-Java · GitHub

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/*
 * Chapter 8.3
 *
 * Connected to this class is a Test2 Class in the
 * HowSubstringsWork folder!
 */
importjava.util.Scanner;
//import java.util.*;

publicclassRecursion
{
publicstaticvoidmain(String[] args)
	{
System.out.println("Pick a number to factorial!");
Scannerin = newScanner(System.in);
intuserNum = in.nextInt();
System.out.println(factorial(userNum) + "\n");

System.out.println("Type in any number to see it in Binary!");
intuserBin = in.nextInt();
binary(userBin);
System.out.println();
in.nextLine();

System.out.println("Please provide a String!");
StringuserStr = in.nextLine();
StringuserLow = userStr.toLowerCase();
System.out.println(noX(userLow));
	}

//"stub"
/*public static int factorial(int n)
	{
 return 0;
	}*/
publicstaticintfactorial(intn)
	{
if(n == 0)
return1;
intsum = n*factorial(n-1);
returnsum;
//return n*factorial(n-1);
	}

publicstaticvoidbinary(intnum)
	{
//(1)WRONG includes the base case BUT prints normal
//Because the f(n) is done before everything but printed after!
//(1)int numToBinary = num % 2;
if(num != 0)
 {
//(2)WRONG prints correctly just backwards because
//it prints before the recursion
//(2)System.out.print(num%2);
binary(num/2);
System.out.print(num%2);
 }
//(1)System.out.print(numToBinary);
//return numToBinary;

/*
 int numToBinary = 0;
 int mod = 0;
 //bad thinking because dividing will bring any
 //number to 1 or 2 NOT 0 or 1 and that last 1 or 0
 //division is important for the one's place!!!
 if(num == 0)
 return 0;
 else if(num == 1)
 return 1;
 else
 {
 mod = num % 2;
 System.out.println(mod);
 numToBinary = binary(num/2);
 System.out.println(mod + "\n\n");
 System.out.println(mod);
 }
 return numToBinary;*/
	}

publicstaticStringnoX(Stringsent)
	{
if(sent.length() == 0)
return"";
//Why can't I use this in the return and why can it be used
//for loop without being initialized 1st??????
StringnoX;
StringabNoX = "";
for(inti = 0; i < sent.length(); i++)
 {
if(sent.charAt(i) == 0 && sent.charAt(i) == 'x')
sent.substring(i+1);
if(sent.charAt(i) == 'x')
 {
//System.out.println(sent);
StringnotX = sent.substring(i+1);
//System.out.println(notX);
noX = sent.substring(0, i) + notX;
//Why does this print out the answer and not our return?
System.out.println(noX);
abNoX = noX(noX);
 }
 }
//System.out.println(noX); ?
returnabNoX;
	}

//How many times the No. 11 appears in an array
publicstaticintarray11(int[] nums, intindex)
	{
if(index >= nums.length)
return0;
intrecurse = array11(nums, index+1);
if(nums[index] == 11)
return (recurse + 1);
else
returnrecurse;
	}
}